Expandable roll core shaft unit

ABSTRACT

A mechanically operated, expandable spool useful as a roll core shaft unit and having a plurality of longitudinally extending segments symmetrically located about a central shaft. A longitudinally movable, tubular member is located intermediate the shaft and segments with cam surfaces disposed to engage follower wheels carried by each of the segments. A drive collar carried by the shaft is threaded to the tubular member to drive the latter longitudinally relative to the segments causing the cam and follower to shift the segments radially and concentrically relative to the shaft to engage and disengage a roll of material. In one form the segments are rectangular bars having sharp corners for positively gripping a roll core carrying the material, and in another form the segments have circular outer surfaces allowing wind-up of the material directly therein.

United States Patent [191 Glaser EXPANDABLE ROLL CORE SHAFT UNIT [75]Inventor: Donald A. Glaser, Emporia, Kans. [73] Assignee: Didde-Glaser,Inc., Lyon, Kans. [22] Filed: Sept. 5, 1972 [21] Appl. No.: 286,216

[52] US. Cl, 242/72 [51] Int. Cl B65h 75/24 [58] Field of Search 242/72,72.1

[56] References Cited UNITED STATES PATENTS 2,335,602 11/1943 Nash242/72 2,558,689 6/1951 Miller 242/72 2,682,924 7/1954 Lomazzo.....242/72 X 3,593,938 7/1971 Watt 242/72 3,637,156 1/1972 Shepherd 242/72.l3,666,194 5/1972 Gosnell 242/72 Primary Examiner-John W. HuckertWilliams [111 3,823,892 [451 July 16, 1974 A mechanically operated,expandable spool useful as a roll core shaft unit and having a pluralityof'longitudi-l nally extending segments symmetrically located about? acentral shaft. A longitudinally movable, tubular, member is locatedintermediate the shaft and segv ments with cam surfaces disposed toengage follower] the segments are rectangular bars having sharp cornersfor positively gripping a roll core carrying the material, and inanother form the segments have circular outer surfaces allowing wind-upof the material directly therein.

' 19 Claims, 9 Drawing Figures PATENTEDJUL 1 61974 SBEEIIBFZ HI nmI m II I I I I I I I I W I IIII I I I I l i I I I n 1 EXPANDABLE ROLL CORESHAFT UNIT v be released from engagement with the roll of material.

Expandable type spools are particularly useful as a roll core shaft unitcarrying rolls of materials that are relatively large and heavy, orwhichare rotated at relatively high speed and thereby must be firmly held inconcentric relationship to the central support shaft. Radial adjustmentof the spool permits firm lockup thereof with a roll core carrying thematerial while permitting selective release of the spool from the rollcore to facilitate easy assembly and disassembly. Accordingly, suchexpandable spools are also particularly useful in winding up discardablematerial into a compact roll due to the Lease in which the spool may bereleased from the roll by radial contraction of the spool.

The only expanding type spoolsn'ow'available that function adequatelyare very expensive, normally being pneumatically or otherwisepower-operated to create concentric expansion and proper lockup with theroll core. Inexpensive, mechanically expandable spools now available aresubject to a variety of problems. Primarily, it is difficult to lock theroll core in proper concentric relationship to the central shaft. Theexpandable spool tends to mount the roll core eccentrically relative tothe shaft and/or cant the roll lengthwise relative thereto, since thespool does not positively locate the roll of material concentric to theshaft. This results in wobbling of the roll of material and makes itdifficult to maintain proper material tension because of theeccentricity. Further, these prior art arrangements will not workproperly with oversized, deformed or out-ofround cores. Certainarrangements will operate in only one directionof rotation of the rollcore with the roll coming loose from the shaft if it is rotated inreverse. Other types, in addition to requiring the use of special tools,are extremely difficult to adjust manually because of small mechanicaladvantage.

Accordingly, it is a broad object of the present invention to provide amechanically operated, expandable spool for use as a roll core shaftunit of inexpensive and simple structure which locks a roll corecarrying a roll of material in concentric, non-canted relationship tothe central support shaft.

It is an important object of this invention to provide a spool which hasradially expandable segments symmetrically disposed about a centralshaft, and a longitudinally movable member located intermediate theshaft and the segments which is engageable with the segments tosimultaneously shift the latter radially and concentrically relative tothe shaft and thereby carry the roll of the material in properconcentric relationship to the shaft, while presenting a simple,inexpensive, and compact arrangement facilitating easy insertion andremoval of the roll of material therein.

A more particular object of the invention is to provide cam surfaces onthe member, and follower wheels on the segments in contact with-thecorresponding cam surfaces to effect concentric radial shifting of thesegments with minimal frictional resistance in response to longitudinalmovement of the member, there being a threaded collar carried by theshaft and in engagement with the tubular member to provide highmechanical '2 advantage in manually shifting the member longitudinally.

Another objectof the invention is to provide means engaging the shaft,the member, and the segments to locate the segments and the tubularmember in symmetric relationship to the shaft to thereby assureaconcentric shifting of the segments. Another important object of theinvention-is to provide segments in the form of a plurality of separatepolygonal, preferably rectangular, bars each of which presents a pair oflocking edges extending longitudinally of the roll core to positivelygrip the latter in nonslipping relationship, even if the roll core isirregular or out-of-round, and thereby positively lock the roll ofmaterial onto the central shaft.

Yet another important object is to provide an expandable spool havingexpandable-segments which are configured to allowv wind-up of materialdirectly thereon into a compact roll so that upon subsequent radialcontraction of the segments the spool may be quickly and easily removedfrom the roll.

Yet another object of the invention is to provide a spool of the typedescribed wherein is included biasing means engaging the severalsegments to urge the latter radially inwardly so that the spool assemblyhas no loose parts.

Another object of this invention is to provide a spool of the classdescribed wherein the segments are selectively longitudinally adjustablein unison relative to the shaft to facilitate positioning of the roll ofmaterial on the-shaft. I

These and other more particular objects and-advantages of the presentinvention are specifically set forth in or will become apparent from thefollowing detailed description of a preferred form of the invention whenread'in conjunction with the accompanying drawings, wherein:

FIG. 1 is a side elevational view, with portions broken away and shownin'cross-section to reveal details of construction, of one form of theinvention as mounted upon supporting machinery;

FIG. 2 is an enlarged, longitudinal, partial central cross-sectionalviewof the unit shown in FIG. 1 with a roll. of material mounted thereon andthe unit in radially expanded condition;

FIG. 3 is a transverse cross-sectional viewtaken along line 3-3 of FIG.1, a roll core being shown mounted thereon;

FIG. 4 is a transverse cross-sectional view taken along line 4-4 of FIG.2;

FIG. 5 is an end elevational view of the supporting machinery and shaftunit with a roll of material mounted thereon;

FIG. 6 is a side elevational view, with portions broken away to revealdetails of construction, of another form of the invention;

FIG. 7 is a transverse cross-sectional view taken along line 7--7 ofFIG. 6;

FIG. 8 is an enlarged, longitudinal, cross-sectional view of the outerend of the shaft un'it shown in FIG. 6; and

FIG. 9 is a transverse cross-sectional view similar to FIG. 4 butshowing a modified form of radially expandable segments.

Referring now more particularly to FIGS. l5, an improved spool in theform of a roll core shaft unit, generally designated by the numeral 10,includes a central shaft 12 which is cradled within a pair of supportbrackets 14 of press machinery 16 or the like. A brake drum 18 at oneend of shaft 12 is engageable by a brake shoe 20 on the machinery, whileat the other end of the shaft a plate 22 fits within a correspondinggroove in the shaft. An adjusting nut 24 extends between plate 22 andone of the support brackets 14 and is adjustable to shift the entireunit longitudinally relative to support brackets 14 and machinery 16. Aroll of material 17 is mountable about unit 10 as shown in FIGS. 2, 4and 5.

Unit 10 includes segment means in the form of three rectangularly-shapedsegment or locking bars 26 which are symmetrically disposed about shaft12 and extend longitudinally therealong. Each bar 26 has a pair ofradially arranged follower wheels 28 rotatably'mounted thereon by smalltransverse spindles 30. As shown in FIG. 1, these wheels 28 dependradially inwardly to engage the outer surface of shaft 12. Each lockingbar 26 also has a pair of apertures 32 which receive alignment roll pins34 which are press-fit into shaft 12. Pins 34 locate the barssymmetrically about the shaft in approximately 120 spacing, align thebars in longitudinally parallel relationship to the shaft 12, and act asmechanism interconnecting shaft 12 and bars 26 to prevent relativelongitudinal movement between the shaft 12 and the bars. ElastomericO-rings 36 are carried in grooves at each end of the bars 26 and extendaround all of the bars to bias the bars 26 radially inwardly toward theshaft.

Located intermediate bars 26 and shaft 12 is a longitudinally movabletubular member in the form of a tube 38 surrounding the shaft. Tube 38has a plurality of l0n gitudinally elongated slots 40 located incorresponding alignment with pins 34 and wheels 28. The pins 34 areloosely received in slots 40 to locate and align tube 38 relative tobars 26 and to hold the tube against rotation relative to shaft 12 andthe bars 26. One end of each slot 40 is inclined to define a cam surface42 for en gagement with the corresponding follower wheel 28. Tube 38 isofa size snugly fitting over shaft 12 but permitting free longitudinalsliding movement of tube 38 along the shaft, with the elongatedconfiguration of slots 40 facilitating longitudinal movement of thetube.

Drive means in the form of an internally threaded collar 44 mounts upona threaded end 46 of tube 38.

Shaft shoulder 48 and snap ring 50 define securing means operablyengaging collar 44 through bearing washers 52 to hold collar 44 againstlongitudinal movement relative to shaft 12 while permitting freerotation of collar 44.

A knurled outer surface 54 on collar 44 permits easy manual rotation ofthe collar to cause 7 longitudinal shifting of tube 38 relative to shaft12 and the bars 26. The screw engagement of collar 44 with tube 38,along with leverage created bythe engagement of the sloped cam surfaces42 with wheels 28, provides high mechanical advantage facilitating easy,powerful radial shifting of bars 26. Collar 44 also has a bore 56 forreceiving a screwdriver or other tool to yet further increase themechanical advantage in shifting bars 26.

In operation, bars 26 are placed in a radially retracted condition asshown in FIG. 1 to facilitate easy mounting of a roll of material 17about unit 10 as illustrated in FIG. 3.Scale graduations 60 on the outersurfaces of bars26 facilitate quick longitudinal centering of the rollcore upon the shaft unit. Upon rotation of collar 44 to advance upon thethreaded end 46, tube 38 moves longitudinally rightwardly along theshaft, causing follower wheels 28 to roll upwardly upon cam surfaces 42.As a result, the three locking bars 26 shift radially outwardly untiltheir corners 62 firmly, positively grip the inside surface of roll core58.

The matching inclines of the several cam surfaces 42 and matchingpositioning of the several follower wheels 28 assure that the three bars26 shift simultaneously. Accordingly, the six core-engaging corners 62shift concentrically and radially relative to the shaft to grip and lockthe roll core 58 in concentric relationship to shaft 12 as shown inFIGS. 2 and 4. While the follower wheels are shown extending slightlyabove the radially outermost surface of the corresponding bar 26, itwill be appreciated that only the corners of bars 62 engage roll core58, with wheels 28 remaining free to rotate upon their spindles 30. Theconcentric radial shifting of the bar segments also assures that theroll core will not be canted lengthwise when locked to unit 10.

The six, concentrically spaced, longitudinally extending comers 62present contact areas at a sufficient variety of points on the innersurface of core 58 to assure firm grippage of roll core 58regardless ofany deformation or irregularity therein. Further, to this end, thediameters of pins 34 and apertures 32 permit a limited amount of playtherebetween so that each bar 26 may rotate slightly about itslongitudinal axis and more readily assure firm lockup of both edges 62of each bar with core 58. The unit will accommodate large variation incore diameter as well as fit out-of-round cores such as those which aredeformed by handling, etc. Shaft 12 is rotatable in either directionwithout affecting the tight interengagement of the locking bars and rollcore.

The compact configuration of unit 10 presents no element which extendsradially outwardly to interfere with insertion and removal of roll 17,and yet presents an arrangement having minimal frictional resistance toradial shifting of the bars and having extremely high mechanicaladvantage to effect such radial shifting. The unit is comprised of fewand inexpensive parts requiring no special tools to operate, and has noparts which are loose from the shaft. The arrangement facilitates fastlockup and quick removal of an old core and replacement with a new roll.Insertion of an elongated tool within bore 56 of collar 44 permits easyaccess to collar 44 even if the roll core extends partially thereover.

Disengagement of the bars 26 from roll core 58 to facilitate removalthereof is accomplished simply by rotating collar 44 in the oppositedirection to retreat upon threaded end .46 to drive tube 38 backleftwardly and permit the follower wheels 28 to roll back down on camsurface 42 under the urging of O-rings 36.

The form of the invention illustrated in FIGS. 6-8 is quite similar tothat above-described, but as modified to be supported from one end onlyand to permit longitudinal adjustment of the core-engaging segmentsrelative, to the central supporting shaft. An expandable spool or rollcore shaft unit 10 illustrated in FIGS. 6-8 has a central shaft 12', alongitudinally movable tube 38', and three rectangular locking bars orsegments 26', all of which operate in a manner similar to thecorresponding elements in the FIG. 1 arrangement. Radially extendingalignment pins 34' pass through corresponding elongated slots 40' in thetube and into longitudinally elongated apertures 32' in the lockingbars. Each locking bar carries cam follower wheels 28' which roll up anddown upon corresponding cam surfaces 42' in the tube 38'. A drive collar44' is in engagement with a threaded end 46 of tube 38.

Unit additionally includes a threaded stop nut 64 which is mounted upona threaded section 66 of shaft 12'. One end of stop nut 64 abuts ashoulder 68 on collar 44 and engages collar 44 in the opposite directionthrough snap rings 70 and thrust bearing 72 to act as means normallysecuring the drive collar 44' against longitudinal movement relative tothe shaft. Also, the drive collar 44' is rotatably carried by shaft 12'through stop nut 64. The inner end of collar 44 abuts the severallocking bars 26 through a thrust bearing 74 so that stop nut 64 alsoacts as mechanism operably engaging locking bars 26' through collar 44to interconnect the bars 26 with the shaft in a manner normallypreventing leftward longitudinal movement of bars 26' relative to shaft12'. The engagement of all of follower wheels 28' with the cam surfacesof tube 38' which, in turn, is threaded to collar 44, normally preventsrightward longitudinal movement of the bars 26 relative to shaft 12.

At the right-hand end of bars 26 there is an annular stop plate 76located radially outwardly of tube 38' and extending outwardly tocontact the end of a material roll 17. Stop plate 76 has three radialgrooves 78 that receive shoulder bolts 80 which are screwed into theends of the three locking bars 26'. The elongated configuration ofgrooves 78 prevents interference with radial shifting of the lockingbars by shoulder bolts 80.

The concentric, radial shifting of locking bars 26 is accomplished inprecisely the same manner as above described with respect to FIGS. l-Sby advancing collar 44' on threaded end 46' of tube 38. In addition tothis, unit 10' permits selective adjustment of the longitudinal positionof bars 26 relative to shaft 12' in order to adjustably position roll17' relative to a fixed support 82. To this end, advancement of stop nut64 upon threaded section 66 pushes collar 44, tube 38, and bars 26 inunison rightwardly toward support 82 to the phantom position shown inFIG. 6. Movement of these three elements in unison maintains the samepositional relationship of follower wheels 28 to the cam surfaces 42'.The elongated apertures 32' permit such longitudinal shifting of bars26. Stop plate 76, the left-hand face of which defines a reference planefor locating roll 17' relative to support 82, moves with bars 26 topermit adjustable positioning of roll 17 relative to the support.

Bars 26 may be moved away from support 82 by rotating collar 64 in theopposite direction to pull collar 44 and tube 38' leftwardly. Engagementof wheels 28' with the corresponding cam surfaces in the tube causes thebars 26 to also move leftwardly in unison with the tube.

The unit 10 maintains all of the advantageous operating and structuralcharacteristics described withrespect to unit 10 of FIG. I. Both collars44 and 64 are located for each access and are of less diameter than thecore of roll 17 to facilitate easy insertion and removal thereof uponunit 10.

FIG. 9 illustrates a modified spool having radially shiftable segmentsin the form of elongated, curved elements 126 having circular outersurfaces 127 that lie in a common circle concentric to central supportshaft 12. The same arrangement of follower wheels 28 contacting camsurfaces on tube 38 effects simultaneous radial shifting of elements 126as effects shifting of bars 26 in FIG. 1. The outer surfaces 127 areofsufficient circumferential width, together forming almost an entirecircle, to allow winding and unwinding of material 117 directly onsurfaces 127. At the same time however, the elements 126 and outersurfaces 127 are spaced from each other to allow radial shifting of theelements.

The FIG. 9 arrangement is particularly useful for coreless winding andunwinding of material as well as in winding up discardable material 117without the use of a central roll core. After winding material 117 onelements 126 into a compact roll, the elements can be radiallycontracted under the urgings of elastomer 0- rings 36 in the mannerdescribed with respect to FIG. 1 to allow removal of the entire spoolfrom the roll so the latter may be discarded. It is also useful forproviding uniform support for relatively weak roll cores which wouldotherwise be unable to properly support the material carried thereon.This modified form retains all the advantages and operational featuresas the previously described forms, except for the use of circularelements 126 instead of the locking bars 26. The circular elements 126may be utilized equally well in conjunction with either the FIG. Iarrangement or the FIG. 6 construction.

Having thus described the invention, what is claimed as new and desiredto be secured by letters Patent is:

1. An expandable spool comprising: an elongated shaft;

a plurality of elongated, rigid, apertured rods positioned incircumferentially spaced relationship about said shaft;

a plurality of pins extending outwardly from said shaft'and received inthe apertures of respective rods;

an axially shiftable sleeve positioned between said shaft and rods, saidsleeve being operable upon axial shifting thereof to engage said rods toeffect simultaneous radial movement of the latter with respect to saidshaft; and

means for axially shifting said sleeve to thereby radially move saidrods. I

2. A spool as set forth in claim 1, wherein said rods are ofsubstantially identical configuration and are symmentrically arrangedabout said shaft.

3. A spool as set forth in claim 2, wherein each of said rods has acylindrical outer surface remote from said shaft.

4. A spool as set forth in claim 2, wherein each of said rods is ofpolygonalcross-section.

5. A spool as set forth in claim 4, wherein said rods is of rectangularcross-section.

6. A spool as set forth in claim 1, wherein said sleeve has slotstherein through which said pins extend to be received in the aperturesof respective rods, said slots being elongated and axially aligned withsaid shaft to permit axially shifting of the sleeve.

7. A spool as set forth in claim 6, wherein said sleeve includes camsurfaces disposed in corresponding relationship to each of said rods,there being a follower carried by each of said rods operable to engagethe corresponding cam surface to effect said simultaneous radialmovement of the rod in response to axially shifting of the sleeve.

8. A spool as set forth in claim 7, wherein each of said followerscomprises a follower wheel rotatably mounted on the corresponding rod.

9. A spool as set forth in claim 2, wherein is provided meanscircumscribing said rods and biasing the same radially inwardly withrespect to said shaft.

10. A spool as set forth in claim 1, wherein is provided mechanisminterconnecting said shaft and said respective rods to prevent relativeaxial movement therebeween.

11. A spool as set forth in claim 10, wherein said mechanism is axiallyadjustable to selectively move said rods axially of the shaft.

12. A spool as set forth in claim 11, wherein said shaft has a threadedsection, said mechanism including an adjustable, threaded stop nutcarried on said threaded section and operably engaging said rods tonormally prevent axial movement thereof, said stop nut being advanceableon said threaded section to move said rods axially relative to theshaft.

13. A spool as set forth in claim 12, wherein said stop nut alsooperably engages said sleeve to axially move the same in unison withsaid rods upon advancement of the stop nut on said threaded section.

14. A spool as set forth in claim 1, wherein said means for axiallyshifting said sleeve includes drive means carried by said shaft.

15. A spool as set forth in claim 14, wherein said drive means is inthreaded engagement with said sleeve and rotatably carried by saidshaft, there being means same relative to the shaft, and means forpreventing rotation of said sleeve relative to the shaft.

16. A spool as set forth in claim 15, wherein said drive means includesa rotatable collar surrounding said shafta'nd in threaded engagementwith said sleeve.

17. A spool as set forth in claim 16, wherein said shaft has a threadedsection thereon, said means for securing said drive means to the shaftincluding a threaded stop nut abutting said collar and carried on saidthreaded section, said collar abutting said rods whereby advancement ofsaid stop nut on said threaded section moves said sleeve and said rodsin unison axially relative to the shaft.

. 18. A spool as set forth in claim 16, wherein said means for securingsaid drive means to the shaft comfor securing said drive means to saidshaft to prevent Y axial movement thereof while allowing rotation of theprises stationary, spaced shoulders on said shaft located to contactsaid collar and permit rotation thereof relative to the shaft.

19. An expandable spool comprising: an elongated shaft; a plurality ofelongated rods positioned in circumferentially spaced relationship aboutsaid shaft; an axially shiftable sleeve positioned between said shaftand rods, said sleeve being operable upon axial shifting thereof toengage said rods to effect simultaneous radial movement of the latterwith respect to said shaft; mechanism interconnecting said shaft androds permitting selective axial movement of the latter with respect tosaid shaft; and 7 means for axially shifting said sleeve totherebyradially move said rods.

1. An expandable spool comprising: an elongated shaft; a plurality of elongated, rigid, apertured rods positioned in circumferentially spaced relationship about said shaft; a plurality of pins extending outwardly from said shaft and received in the apertures of respective rods; an axially shiftable sleeve positioned between said shaft and rods, said sleeve being operable upon axial shifting thereof to engage said rods to effect simultaneous radial movement of the latter with respect to said shaft; and means for axially shifting said sleeve to thereby radially move said rods.
 2. A spool as set forth in claim 1, wherein said rods are of substantially identical configuration and are symmentrically arranged about said shaft.
 3. A spool as set forth in claim 2, wherein each of said rods has a cylindrical outer surface remote from said shaft.
 4. A spool as set forth in claim 2, wherein each of said rods is of polygonal cross-section.
 5. A spool as set forth in claim 4, wherein said rods is of rectangular cross-section.
 6. A spool as set forth in claim 1, wherein said sleeve has slots therein through which said pins extend to be received in the apertures of respective rods, said slots being elongated and axially aligned with said shaft to permit axially shifting of the sleeve.
 7. A spool as set forth in claim 6, wherein said sleeve includes cam surfaces disposed in corresponding relationship to each of said rods, there being a follower carried by each of said rods operable to engage the corresponding cam surface to effect said simultaneous radial movement of the rod in response to axially shifting of the sleeve.
 8. A spool as set forth in claim 7, wherein each of said followers comprises a follower wheel rotatably mounted on the corresponding rod.
 9. A spool as set forth in claim 2, wherein is provided means circumscribing said rods and biasing the same radially inwardly with respect to said shaft.
 10. A spool as set forth in claim 1, wherein is provided mechanism interconnecting said shaft and said respective rods to prevent relative axial movement therebeween.
 11. A spool as set forth in claim 10, wherein said mechanism is axially adjustable to selectively move said rods axially of the shaft.
 12. A spool as set forth in claim 11, wherein said shaft has a threaded section, said mechanism including an adjustable, threaded stop nut carried on said threaded section and operably engaging said rods to normally prevent axial movement thereof, said stop nut being advanceable on said threaded section to move said rods axially relative to the shaft.
 13. A spool as set forth in claim 12, wherein said stop nut also operably engages said sleeve to axially move the same in unison with said rods upon advancement of the stop nut on said threaded section.
 14. A spool as set forth in claim 1, wherein said means for axially shifting said sleeve includes drive means carried by said shaft.
 15. A spool as set forth in claim 14, wherein said drive means is in threaded engagement with said sleeve and rotatably carried by said shaft, there being means for securing said drive means to said shaft to prevent axial movement thereof while allowing rotation of the same relative to the shaft, and means for preventing rotation of said sleeve relative to the shaft.
 16. A spool as set forth in claim 15, wherein said drive means includes a rotatable collar surrounding said shaft and in threaded engagement with said sleeve.
 17. A spool as set forth in claim 16, wherein said shaft has a threaded section thereon, said means for securinG said drive means to the shaft including a threaded stop nut abutting said collar and carried on said threaded section, said collar abutting said rods whereby advancement of said stop nut on said threaded section moves said sleeve and said rods in unison axially relative to the shaft.
 18. A spool as set forth in claim 16, wherein said means for securing said drive means to the shaft comprises stationary, spaced shoulders on said shaft located to contact said collar and permit rotation thereof relative to the shaft.
 19. An expandable spool comprising: an elongated shaft; a plurality of elongated rods positioned in circumferentially spaced relationship about said shaft; an axially shiftable sleeve positioned between said shaft and rods, said sleeve being operable upon axial shifting thereof to engage said rods to effect simultaneous radial movement of the latter with respect to said shaft; mechanism interconnecting said shaft and rods permitting selective axial movement of the latter with respect to said shaft; and means for axially shifting said sleeve to thereby radially move said rods. 